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CHAPTER 7 (ELECTRIC & MAGNETISM) PAPER 1 1. When the switch is on, the current that flows in an electronic advertisement board is

3.0 x 10 -5 A. What is the number of electrons flowing in the advertisement board when it is switched on for 2 hours ? [ Charge of an electron is = 1.6 x 10 -19 C]

SPM 2004 A 3.84 x 10 11 B 1.67 x 10 14 C 1.35 x 10 18 D 4.17 x 1023 E 1.50 x 10 27

2. The electric current supplied by a battery in a digital watch is 3.0 x 10 -5 A.

What is the quantity of charge that flows in 2 hours ? SPM 2005

A 2.5 x 10 -7 C B 1.5 x 10 -5 C C 6.0 x 10-5 C D 3.6 x 10-3 C E 2.2 x 10-1 C

3. Which diagram shows the correct electric field pattern ? SPM 2003

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4. Which graph shows the relationship between potential difference , V , and current , I ,

for a resistor that obeys Ohm s law ? SPM 2003

5. Which circuit can be used to determine the resistance of a bulb ? SPM 2003

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6. The diagram shows a circuit containing four bulbs A, B ,C and D, which are lit at

normal brightness. When a bulb is faulty ,no current will flow through it. Which bulb , when faulty will cause all the bulbs not to light up ?

SPM 2004

7. All the bulbs below are identical. SPM 2004

Which of the following statements is true ? A Reading of A1 > A 2 > A3 B Reading of A1 > A3>A2 C Reading of A2>A1>A3 D Reading of A3>A1>A2

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8 The bulb in the circuit is lit at normal brightness when switches S1 and S2 are closed.

SPM 2004

What happens to the brightness of the bulb if only S 1 or S2 is closed ? Only S1 is closed Only S2 is closed A Increases Decreases B Increases Increases C Decreases Increases D Decreases Decreases 9 The electromotive force and internal resistance of the dry cell in the circuit below is 1.5

V and 0.5 respectively. SPM 2004

What is the reading of the voltmeter when the switch is closed ? A 0 V B 1.5 V C Less than 1.5 V D More than 1.5 V

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10. Which circuit can be used to determine the electromotive force of a battery ? SPM 2005

11 The diagram shows a bird perched on a high voltage cable.

SPM 2005

The bird does not experience an electric shock because A the potential difference across X and Y is high B the resistance of the cable across X and Y is very high C the body of the bird has a low resistance D the current flowing through its body is very small.

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12. The table shows the electrical energy consumption tariff.

Calculate the cost in RM of using a 1.5 kW refrigerator for 360 hours. A 84.00 B 90.00 C 118.80 D 129.00 E 135.00

13. The diagram shows an arrangement of apparatus to study the pattern of magnetic fields which are formed when current flows through conductors.

SPM 2004

Which magnetic pattern is formed on the cardboard when both switches are closed ?

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14. The diagram shows an electromagnet.

SPM 2005

Which factor does not influence the strength of the electromagnet ? A Material used for the wire B Material used for insulator of the wire C Number of turns of wire D Current flowing in the wire..

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15. When the switch is closed in the circuit below , wire R deflects. SPM 2004

The direction of the deflection cannot be determined by A Fleming s right hand rule B Flemings left hand rule C Maxwell s corkscrew rule 16. The diagram shows a coil of wire placed next to a magnet. The galvanometer pointer

deflects when the magnet is pushed into the coil. SPM 2004

Which action will increase the deflection of the galvanometer pointer ? A The magnetic pole is reversed B The number of coils is increased C The coil is made from insulated wire D The magnet is pushed slowly into the coil.

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17. The diagram shows a magnet oscillating in a solenoid.

Which of these will not increase the deflection of the galvanometer pointer ? A Reversing the polarity of the magnet B Increasing the number of coils in the solenoid C Decreasing the diameter of the solenoid D Increasing the oscillation speed of the magnet.

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18 Which diagram shows the correct direction of the induced current when the magnet is

moved in the direction shown ? SPM 2005

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19. The diagram shows the structure of an ideal transformer

SPM 2005

What is the potential difference across the bulb ? A 7 V B 24 V C 30 V D 60 V E 160 V

20. The diagram shows a circuit containing an ideal transformer.

Which statement is correct about the brightness of bulb P and bulb Q ? A Bulb P is brighter than bulb Q B Bulb P and bulb Q have the same brightness C Bulb Q is brighter than bulb P

21. The diagram shows the structural design of an electric motor.

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22. The diagram shows an electric generator connected to a cathode ray oscilloscope.

Which trace represents the e.m.f induced in the generator when the coil is rotated at a constant speed.?

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PAPER 2 ( SECTION A) SPM 2006 1. Diagram 1.1 shows an electric circuit.

(a) (i) Name instrument Q .......................................................................................................... [ 1 mark]

(ii) What is the function of R in the circuit ? ......................................................................................................... [1 mark]

(b) Diagram 1.2 show two types of ammeters , X and Y , that can be used in the circuit in Diagram 1.1

(i) Which ammeter is more sensitive ? ............................................................................................................... [1 mark] (ii) State one reason for your answer in 1 (b) (i) . ................................................................................................................ [1 mark]

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SPM 2004 Figure 8.1 shows an immersion heater with specification of 240 V , 1000 W.

(a) Name one suitable material to be used as a heating element in the immersion heater. ....................................................................................................................................... [ 1 mark] (b) The immersion heater is connected to a 240 V supply. Calculate ;

(i) the current that passes through the immersion heater , [2 marks] (ii) the resistance of the immersion heater. [ 2 marks] (c) A student conducts an experiment to compare the heating effect of immersion

heaters P ,Q and R. The volume and initial temperature of the water is fixed. Table 8.1 shows the result of the experiment.

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Immersion heater

Potential difference / V Current / A Time for the water to start boiling / minute

P 240 6.0 8.0

Q 240 5.0 10.0

R 240 4.0 9.0

(i) State the energy change that occurs when the immersion is switched on. .................................................................................................................... [1mark]

(ii) Calculate the energy supplied by each of the immersion heaters P ,Q and R to start boiling the water.

[ 4 marks]

(iii) Using your answer in (c) (ii) , suggest which immersion heater is the most suitable to heat water. Give one reason for your answer.

........................................................................................................................... ........................................................................................................................... ........................................................................................................................... [2 marks]

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PAPER 2 (SECTION B) SPM 2003 Figure 16 and Figure 18 show photographs of two circuit. Each circuit contains four identical bulbs connected to four identical new dry cells. (a) (i) State the energy transformation that take place in the bulb [ 1 mark] (ii) Draw a circuit diagram for each photograph. [ 3 marks]

(b) (i) Observe the photographs in Figure 16 and Figure 17. Compare the brightness of the bulbs. Relate the brightness of the bulbs between Figure 16 and Figure 17 to deduce a concept in physics with regard to the potential difference and the current flow for the bulbs in series and parallel circuits. [6 marks] (c ) Figure 18 shows a model of an incubator used to hatch eggs. The temperature in the

incubator must be maintained around 39 C. Every part of the eggs must receive uniform heat. The eggs are hatched in about 20 days.

Using an appropriate concept in physics , explain the modification required to the above incubator so as to efficiently hatch about 200 eggs. [ 10 marks]

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SPM 2005 Most of our electrical energy comes from hydroelectric power stations and thermal power stations. These power stations are connected by cables to transmit electricity to users in industries , offices , schools and houses. This system is called the national grid network. (i) State the transformations of energy in a hydroelectric power station. [ 1 mark] (ii) Explain briefly the importance of the national grid network system in distributing

electrical energy to the users. [ 4 marks] Figure 12.1 shows how a model of an electric transmission system can be set up in laboratory. The model consists of a power station that generates 12 V of alternating current ( a.c) that transmits the electrical energy to the users using transmission wires and transformers P ,Q and R.

You are required to set up a model as in Figure 12.1 using the information in Table 12.1

Type of transformer core

Solid cuprum core Laminated cuprum core Solid soft iron core Laminated soft iron core

Number of turns of the coil

1200 1000 500 400 160 120

.

Materials of transmission wire

Constantan Copper Aluminium Nichrome

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(b) Using the information in Figure 12.1 and Table 12.1 determine : (i) the numbers of turns in the primary and the secondary coil of transformers P, Q

and R and show your working, (ii) the type of core you will use in all the transformers and justify your choice, (iii the material you will use for the transmission wire and justify your choice. [10 marks] (c) If the resistance of the transmission wires between transformers P and Q in the model

at is 30 , calculate :

(i) the current that flows in the transmission wire, (ii) the power loss due to the heating effect of the current in the transmission wire.

[ 5 marks] SPM 2006 Diagram 10.1 and Diagram 10.2 show wire coils connected to the ammeters , switches and d. c power supply.

When the switch is on and iron filings of the same amount is spread on each of the

cardboard surface, the pattern of the iron filings is formed as shown in the diagrams. (a) What is meant by magnetic field ? [1 mark] (b) Using Diagram 10.1 and Diagram 10.2 , compare the number of turns of the coils,

the pattern of the iron filings and angle of deflection of the ammeter indicator. [ 3 marks]

(c) State the relationship between the strength of the magnetic field and

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(i) the pattern of the iron filings (ii) the number of turn of the coils [2 marks]

(d) Diagram 10.3 shows two thin copper strips , PQ and RS , connected to a circuit.

Explain what happens to PQ and RS , when the switch is on. [ 4 marks]

(e) Diagram 10.4 shows an electric motor which is supplied with a 12 V a.c

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(i) Explain how the motor is able to rotate (ii) Using a 12 V a.c power supply , explain the modification that needs to

be done on the motor and the external circuit to enable the motor to be a d.c electric motor and rotate faster.

[6 marks]

SPM 2004 Figure 4.1 shows circuits J,K , L, M and N each containing an ideal transformer. Diodes in

the circuits are used for the purpose of rectification.

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(i) What is meant by rectification ? (ii) Explain the working principle of a transformer. (iii) You are asked to make a 12 V battery charger. Study the circuits , J ,K,L , M

and N in Figure 4.1 and consider the following aspects : - type of transformer - ratio of number or turns in primary coil to secondary coil - type of rectification - characteristic of output current.

Explain the suitability of the above aspects and hence determine the most suitable circuit to make the battery charger. Justify your choice. [10 marks]

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(b) Figure 4.2 shows a circuit consisting of a transformer , an ammeter and two light bulbs. The ammeter reading is 0.5 A and both light bulbs light up with normal brightness.

(i) What is the output of the transformer ? (ii) Calculate the efficiency of the transformer ?